Nutrition, Energy Balance Lecture 10

Nutrition Concepts & Controversies: Energy Balance

• Energy Balance is the relationship between energy intake and energy expenditure.
• A change in stored energy equals energy intake minus energy expenditure.
• A mismatch in energy balance compounds over time.
• Energy balance involves factors such as protein, carbohydrates, fat, alcohol, basal metabolic rate (BMR), thermic effect of food (TEF), and physical activity.

Learning Goals

• Identify health risks associated with inadequate and excessive body fat.
• Explain the concept of energy balance and related factors.
• Correlate body weight, body fat, and implications for health using BMI.

Body Composition

• Normal body fat percentages vary by sex related to reproductive function.
  • Males: 12%-20%
  • Females: 20%-30%
• Body composition consists of muscle, organs, fat, bone.

Average Body Composition of Men and Women

• Men: 45% muscle, 25% organs, 15% fat, 15% bone
• Women: 36% muscle, 24% organs, 27% fat, 13% bone

The Body's Energy Balance

• Energy balance is the relationship between energy intake and energy expenditure.
• Factors include protein, carbohydrates, fat, alcohol, basal metabolic rate (BMR), thermic effect of food (TEF), and physical activity.
• Change in energy stored = Energy in - Energy Out

Assessing Where Someone Is At

• Body Composition: The proportion of muscle, bone, fat, and other tissue in a person's body.
• Body Mass Index (BMI) : A measure of body fat based on height and weight. Not accurate for athletes.
  • Underweight: <18.5 kg/m²
  • Normal weight: 18.5-24.9 kg/m²
  • Overweight: 25.0-29.9 kg/m²
  • Obese Class I: 30.0-34.9 kg/m²
  • Obese Class II: 35.0-39.9 kg/m²
  • Obese Class III: ≥40.0 kg/m²
• Waist Circumference: A measure of abdominal fat, used to assess health risk.
  • Waist circumference is a risk factor for health problems

BMI Categories and Health Risk Levels

• BMI (kg/m²) categories and associated health risk levels vary from underweight to obese class III, with increasing risk as BMI increases or decreases from a healthy range.

How Obesity is increasing

• In 2016-2017, 26.9% of the Canadian population was obese. This represents a marked increase compared to past decades.

Body Fat Distribution

• Upper body fat distribution is more related to health risks compared to lower body fat distribution (pear-shaped versus apple-shaped body type).

Where We Carry Fat Can Matter

• Visceral fat (inside abdomen) is more problematic than subcutaneous fat (under skin).
• Abdominal obesity is a considerable risk factor for several health issues.

Some Health Risks from Overweight or Obesity

• Cardiovascular disease
• Hypertension
• Diabetes
• Abdominal Hernias
• Arthritis
• Complications of pregnancy
• Gallbladder disease
• Certain Cancers
• Kidney Stones
• Liver malfunction
• Respiratory problems
• Varicose veins
• Flat feet

###Some Health Risks from Being Underweight

• Loss of body tissues (muscle, fat, brain, hair)
• Slowing growth/development
• Lower basal metabolism
• Weakened heart, electrolyte imbalances, low blood pressure
• Slowed digestion
• Anemia and altered blood lipids
• Potential fatal outcomes

Determining Energy Expenditure

• Basal Metabolic Rate (BMR): The rate at which the body uses energy for involuntary activities to survive (e.g., breathing, heart rate).
• Thermic Effect of Food (TEF): The increase in metabolism due to digestion and processing food. Around 5-10% of food calories are used.
• Physical Activity: The energy expenditure during exercise and non-exercise activities (NEAT).

How Do We Determine Energy Needs?

• Estimated Energy Requirements (EER): A common method used to determine energy needs based on age, gender, weight, height, and physical activity.
• Other formulas like Harris-Benedict and Cunningham Equations can also be used.
• Quick estimates like calories per kg body weight can also be considered.

Factors Affecting BMR

• Age, height, growth, body composition, fever, stress, environmental temperature, fasting/starvation, and thyroxine levels affect BMR.

Estimating Energy Requirements

• Average dietary energy intake predicted to maintain energy balance. Calculations based on age, gender, weight, height, and activity levels.

How Do We Determine Energy Intake

• Using calories on package labels and food breakdown.
• Using food records to log intake.
• Using a nutrition analysis tool.
• Using nutrition databases to identify nutrient contents and calculate calorie counts.

Energy Density

• Energy density is a measure of the energy provided by a food relative to its weight.
• High-fat, low-fiber foods typically have high energy density, while high-fiber, low-fat foods have low energy density. High-water content foods also have low energy density.
• Example high-energy density foods: chocolate, chips, pretzels

Nutrient Density

• Nutrient density is a measure of the nutrients provided by a food relative to its calorie content.
• Foods high in vitamins, minerals, and fiber are considered nutrient-dense.
• Choosing appropriately nutrient dense foods enhances health while maintaining calorie goals.